<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./script/jquery.js"></script>
    <style>
        div{
            width: 100px;
            height: 100px;
            border: 1px solid greenyellow;
        }
    </style>
</head>
<body>
    <div class="box">
        <button>按钮</button>
    </div>
    <div class="box">
        <button>按钮</button>
    </div>
    <div class="box">
        <button>按钮</button>
    </div>

    <script>
        // find修改子集
        $(".box").click(function(){
            $(this).find("button").css("background-color","green")
        })
        // parent 修改父级
        $("button").click(function(){
            $(this).parent(".box").css("background-color","green")
        })
    </script>
</body>
</html>